This invention relates generally to the field of machining edges of work pieces, and more particularly, to a novel and advantageous method of producing a uniform machine chamfered edge on work pieces having at least one non-linear longitudinal edge and the apparatus for carrying out the method.
In the nuclear energy industry it is necessary to use radioactive fuel rods which are held in bundles of parallel rods clamped together by metal bands or holders. These bundles of rods must be vertically submerged in coolant water. It is preferable that the band which wraps around a fuel rod bundle have a chamfered or angled edge so as to create less turbulence as the bundle is lowered vertically into the coolant. In order to properly manufacture such a fuel rod band it is necessary to start with a flat, metal blank which has non-linear (curved) longitudinal edges. However, in the conventional skiving process for machine cutting or chamfering a blank edge the cutting tool moves along a straight line such that skiving or chamfering of a non-linear edge will produce a final edge which is linear, albeit having the proper chamfered angle. Thereafter, in forming the fuel rod band, the blank is not of the proper form. That is, in order to meet finish component dimensional requirements after forming, the opposing, longitudinal edges of the flat metal blanks cannot be parallel at the time the chamfers are produced. Yet the conventional chamfering process itself produces such parallel longitudinal edges.
Accordingly, it is among the several objects of the present invention to provide a new machine apparatus and a process for using the new apparatus so as to produce nuclear fuel rod holders formed from flat longitudinal blanks having non-linear longitudinal edges such that the metal blanks so produced retain the original non-linear edge shape yet have a chamfered angle which is the same along the entire non-linear edge. It is intended that the apparatus be capable of use for chamfering a single non-linear longitudinal blank edge or of simultaneously chamfering both opposing edges of the blank when such edges are transversely, symmetrically irregular. It is further intended that the blank so chamfered will meet finished component dimensional requirements after forming of the edge.
In furtherence of these objects the present invention comprises, briefly, a machine device for providing uniform, precision chamfered edges upon flat pieces having a non-linear longitudinal edge. The device includes means for holding a flat, flexible blank having longitudinal edges, at least one of which edges is non-linear and to be machined so as to be chamfered, and means for longitudinally fixing the blank relative to the means for holding the blank. Means are provided for non-planar clamping the blank such that a non-linear longitudinal edge of the blank extends by a substantially equal distance at each point thereon into a planar machining path extending along the non-linear longitudinal edge. Further means are provided for linearly passing a straight-edged machine tool along the planar machining path in contact with the non-linear edge for precisely and uniformly machining the chamfer therealong.
It is also intended to accomplish the above objects by a machine process for providing at least one uniform, precision machined chamfers upon a flat piece having at least one non-linear longitudinal edge. The process includes providing a flat, flexible metal blank having two longitudinal edges, at least one such edge being non-linear and to be machined. The blank is placed upon a holding device such that a lower flat surface of the blank is adjacent to a non-planar lower clamping surface of the holding device. The blank is longitudinally fixed relative to the holding device and clamped between an upper clamping surface of the holding device and an opposed correspondingly non-planar lower clamping surface by flexibly deforming the blank between the opposed upper and lower clamping surfaces such that the at least one non-linear longitudinal edge of the blank extends by a substantially equal distance at each point thereon into a planar machining path extending along the non-linear longitudinal edge. A straight-edged machining tool is passed linearly along a planar cutting path in contact with the non-linear edge whereby precisely and uniformly to machine the chamfer therealong.
Other objects and features will be in part apparent and in part pointed out hereinbelow.